Electrocardiograms are typically generated by an electrocardiograph under a 12-lead format. Cardiac signals detected among the leads of the electrocardiograph are typically no more than a few millivolts in magnitude.
The generation of electrocardiograms is subject to a number of difficulties. For example, the heart is a relatively small muscle compared to other muscles of the body. As a consequence, cardiac signals may be overwhelmed by signals generated by other muscles or by noise in general.
Electrocardiograms are typically generated on a moving paper strip using a pen for each lead. In the case of a 12-lead electrocardiogram 12 pens are required. Because of the number of signals, prior art electrocardiographs have generally been relatively large with limited mobility. The limited mobility of electrocardiographs has generally limited their usefulness to hospitals and ambulances. Because of the importance of cardiac monitoring, a need exists for more mobile electrocardiographs.